Locusts and drought have obliterated agricultural production in Mauritania, leaving 400,000 people in urgent need of food aid, the UN food agency says.
A swarm of locusts can devour as much crop as 2,500 people
Mauritania was the country worst hit by last year's locust invasion in West Africa - the most serious infestation in 15 years.
Some 60% of Mauritania's population will not have enough to eat this year, says the World Food Programme.
The WFP appealed for $31m to fund a two-year aid project.
Huge swarms devoured crops in all Mauritania's agricultural regions and invaded the capital, Nouakchott, three times, eating every green plant from the president's gardens to the main soccer pitch.
Insufficient rain compounded the situation
Those in the south, where the infestation was worst, rely almost entirely on farming for income.
"Entire harvests, where the people have invested their money, time and toil for so long, are simply gone. We must act now," Sory Ouane said.
"The right assistance now for the people of Mauritania will go a long way - not only to save lives today but also to help people avoid falling into a cycle of food crises that could last for years to come."